CH. XIX.] OBNOXIOUS INSECTS. 271 



of London. In many parishes subscriptions were 

 opened, and the poor people employed to cut off and 

 collect the webs at one shilling per bushel, which 

 were burnt under the inspection of the parish offi- 

 cers. At the first onset fourscore bushels were 

 collected in one day in the parish of Clapham. 

 Some writers went so far as to assert that they 

 were a usual presage of the plague, others that they 

 would destroy all kinds of vegetables, and thus 

 starve the cattle in the fields. Prayers were even 

 offered up in some churches, on account of their great 

 number, which was considered by some sufficient to 

 render the air pestilential. This idea is founded on 

 the grossest ignorance, and carries with it its own 

 refutation; the health of the pubhc was by no 

 means affected by them, either immediately or re- 

 motely. 



The pest which caused these ravages and fright, 

 is the caterpillar of the brown-tailed moth, the young 

 caterpillars of which are hatched early in autumn. 

 As soon as they quit the egg they set about spinning 

 a web, and having formed a small one, they proceed 

 to feed on the foliage, by eating the upper surface 

 and fleshy part of the leaf, and leaving the under 

 side and ribs. It is curious to observe with what 

 regularity they marshal themselves for this purpose. 

 Thus they proceed daily, spinning and enlarging 

 their web, to which they retreat every night and in 

 bad weather, and extending their depredations. In 

 the course of a few weeks their operations begin to 

 be visible on the trees ; their web as yet is not so 

 conspicuous, as those leaves which are stripped 

 of their green part assume a dead appearance. 

 Now is the time to destroy them, while their nest is 

 small, and their ravages just visible, by collecting 

 the twigs and branches on which they lie hid in their 

 web, and then burning them, merely to prevent their 

 returning again to the trees and shrubs. If this op- 

 eration is performed early it will save the autumnal 



